Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 28 Nov 2018 15:42:31 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     =?iso-8859-1?Q?J=FCrg?= Billeter <j@bitron.ch>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Eric Biederman <ebiederm@xmission.com>,
        Kees Cook <keescook@chromium.org>,
        Andy Lutomirski <luto@kernel.org>, linux-api@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT
Message-ID: <20181128144230.GG30395@redhat.com>
References: <20181127225408.7553-1-j@bitron.ch>
 <20181127225408.7553-2-j@bitron.ch>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20181127225408.7553-2-j@bitron.ch>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 11/27, J?rg Billeter wrote:
>
> @@ -704,6 +713,9 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
>  	struct task_struct *p, *n;
>  	LIST_HEAD(dead);
>  
> +	if (group_dead && tsk->signal->kill_descendants_on_exit)
> +		walk_process_tree(tsk, kill_descendant_visitor, NULL);

Well, this is not exactly right, at least this is suboptimal in that
other sub-threads can too call walk_process_tree(kill_descendant_visitor)
later for no reason.